Managing Winter Lawn Diseases: Your Guide to a Healthy Winter Lawn

A lush, green lawn is the pride of homeowners year-round, and while many of us focus on lawn care during the warmer months, maintaining a healthy lawn in the winter is equally important. Winter may seem like a time of rest for your lawn, but it can also be a period of vulnerability when various lawn diseases can strike, turning your green oasis into a patchy, unhealthy mess.

Winter lawn diseases, although less well-known than their summer counterparts, can significantly impact the beauty and health of your lawn. Gray Snow Mold, Pink Snow Mold, Winter Brown Patch, and other fungal invaders can wreak havoc on your grass, leaving behind unsightly patches, weakened turf, and potential long-term damage.

In this guide, we will explore winter lawn diseases, helping you understand what they are, how to identify them, and, most importantly, how to prevent and treat them effectively.

What Are Winter Lawn Diseases?

Winter lawn diseases, as the name suggests, are a group of fungal and microbial infections that affect grass and lawns during the year’s colder months. These diseases are often overlooked, as many folks associate lawn problems with the warmer seasons. However, understanding and addressing winter lawn diseases is crucial for maintaining a healthy, vibrant lawn year-round.

Types of Winter Lawn Diseases

Gray Snow Mold, also known as Typhula blight, is a fungal disease primarily affecting cool-season grasses during winter. It typically appears as circular, grayish-white patches in the lawn. The affected areas may have a matted, moldy appearance, and fungal mycelium may be visible on the grass blades. Gray snow mold is often seen when snow cover lingers into the spring.

It primarily affects cool-season grasses, including Kentucky Bluegrass, Perennial Ryegrass, and Fine Fescues. It is less common on warm-season grasses.

Gray Snow Mold fungi survive as mycelium or spores in the thatch and soil. When snow accumulates, these dormant spores become active, and the disease develops. The fungus produces enzymes that break down plant tissues and feed on the grass. The disease progresses slowly during the winter but becomes evident when the snow melts.

Gray Snow Mold is primarily a cosmetic issue and typically doesn't cause severe long-term lawn damage. However, preventative measures are crucial to minimize its impact, especially in regions prone to extended snow cover during the winter.

Gray Snow Mold
Gray Snow Mold


Pink Snow Mold, or Fusarium Patch or Microdochium Patch, is another prevalent winter lawn disease typically occurring in cool and moist conditions during late fall, winter, and early spring. The most distinctive feature of this fungi is the pink to reddish coloration of the fungal mycelium and spore masses on the grass blades. Affected areas often appear circular or irregular and range from a few inches to several feet in diameter.

As the snow melts, the pink coloration becomes more apparent. Pink snow mold often rears its ugly head when there's a prolonged snow cover or when the ground is wet from rainfall or irrigation in the absence of snow. Fungal growth is most active when temperatures are around 32°F to 45°F (0°C to 7°C).

Like Gray Snow Mold, Pink Snow Mold primarily affects cool-season grasses such as Kentucky Bluegrass, Perennial Ryegrass, and Fine Fescues and is less common on warm-season grasses. 

Pink Snow Mold
Pink Snow Mold


Winter Brown Patch manifests as irregularly shaped, straw-colored, or brown patches in the lawn during cool, wet winter and early spring conditions. It primarily affects cool-season grasses and can cause significant damage if left untreated. Grass in affected areas may appear sunken and matted down. It's a close relative of the more familiar summer brown patch.

The affected areas can range from a few inches to several feet in diameter. The edges of the patches may have a dark, water-soaked appearance with a red or purple tinge.

Once again, it’s the cool-season grasses that are primarily affected by this lawn disease, including Kentucky Bluegrass, Perennial Ryegrass, and Fine Fescues. However, Chewings Fescue, Creeping Red Fescue, and Hard Fescue are more resistant to Winter Brown Patch and Dollar Spot. It strikes when there's an extended period of wet weather or snow cover on the lawn. Fungal activity is most active when temperatures range from 40°F to 60°F (4°C to 15°C).

The disease progresses slowly during the winter and becomes more noticeable as the weather warms and the grass attempts to grow. Winter Brown Patch can be damaging to lawns if not addressed promptly. Prevention and early intervention are crucial to minimizing its impact, especially in regions with wet and cool winter conditions.

Winter Brown Patch
Winter Brown Patch

Why Winter Lawn Diseases Are a Concern

Winter lawn diseases are concerning for several reasons:

  • They can lead to unsightly and damaged lawns, affecting the overall aesthetics of your property.
  • Infected areas can weaken the grass making it more susceptible to further damage from pests and diseases.
  • If left untreated, winter lawn diseases may result in long-term damage that requires extensive lawn renovation in the spring.

Understanding the types of winter lawn diseases and their characteristics is the first step in effectively managing them.


Related reading: Your Ultimate Winter Lawn-Care Guide


Factors Contributing to Winter Lawn Diseases

winter lawn

Winter lawn diseases can take hold and thrive under specific environmental conditions resulting from poor lawn care practices. Understanding the factors contributing to the development of these diseases is essential for effective prevention and management. Let's explore the key factors that make your lawn susceptible to winter diseases:

Environmental Factors

  • Moisture: Winter lawn diseases often thrive in wet or excessively moist conditions. Snow cover, rainfall, or poor drainage can create a moist environment that encourages fungal growth. Inadequate snowmelt drainage can also exacerbate the issue.
  • Extended snow cover: Prolonged snow cover provides a protective environment for fungal spores to flourish beneath the snow. As the snow melts, it can reveal patches of diseased grass.
  • Low temperatures: Cold temperatures can slow the grass's natural defense mechanisms, making it more vulnerable to diseases. Additionally, some winter lawn diseases are cold-tolerant and thrive in these conditions.

Lawn Care Practices

  • Excessive thatch: Thatch buildup, a layer of dead grass and organic matter, can create a conducive environment for winter lawn diseases. Thatch traps moisture and insulates the grass, promoting disease development.
  • Improper mowing: Mowing your lawn too short in late fall can weaken the grass and make it more susceptible to disease. Grass with shorter blades is also more susceptible to cold damage.
  • Neglected lawn care: Lack of proper winterization, such as fertilization, aeration, and overseeding, can leave your cool-season lawn ill-prepared to withstand winter stress and diseases.
  • Poor soil health: Compacted or nutrient-deficient soil can weaken grass and contribute to disease susceptibility. Well-aerated, well-draining soil is crucial for healthy winter turf.

Lawn Type and Grass Species

Certain grass species may be more or less susceptible to specific winter lawn diseases. Understanding the type of grass in your lawn can help you anticipate potential disease risks and tailor your lawn care practices accordingly. Cool-season grasses are often more susceptible to winter lawn diseases, but that does not mean that warm-season grasses are not at risk — if the conditions are right for fungi, they will latch onto your grass.

When it comes to cool-season grasses, Kentucky Bluegrass is known for its overall disease resistance, including its ability to withstand some common lawn diseases like rust and dollar spot. It is often used in northern regions with cool climates. Perennial Ryegrass is known for its resistance against diseases like Brown Patch and Rust, but it is more susceptible to Pink and Gray Mold. It's commonly used for overseeding in cool-season lawns.

As for warm-season grass, Zoysia, Bermuda, Bahia Grass, and Tall Fescue are generally more resistant to diseases, especially Brown Patch and Dollar Spot.

Local Climate

The local climate plays a significant role in the prevalence of winter lawn diseases. Regions with prolonged snow cover, high humidity, and cold temperatures are more prone to these issues. Being aware of your region's climate patterns can help you prepare and take proactive measures.


Related reading: Complete Guide to Identifying, Fighting and Preventing Lawn Diseases


Prevention Strategies

Prevention Strategies

Preventing winter lawn diseases is the most effective way to ensure a healthy and vibrant lawn during the colder months. Implementing proactive strategies and good lawn care practices can significantly reduce the risk of disease development.

Proper Lawn Care


  • Continue regular mowing at a height appropriate for your grass type until the lawn goes dormant.
  • Avoid cutting the grass too short in late fall, as this can weaken it and make it more susceptible to disease.


  • Schedule lawn aeration in late summer or early fall to improve soil drainage and reduce thatch buildup.
  • Aerating the lawn helps create a healthier root system and improves air circulation.


  • Overseed your cool-season lawn with disease-resistant grass varieties in early fall.
  • Ensure good seed-to-soil contact for optimal germination.


  • Apply a balanced, slow-release fertilizer in late summer or early fall to strengthen the grass before winter.
  • Avoid excessive nitrogen at this time, as it can promote growth that is more susceptible to disease.

Snow Management

Snow Removal

  • Promptly remove snow from your lawn to discourage disease development. Snow cover can provide a protective environment for fungal spores.
  • Use a snow blower or a snow shovel to clear snow, taking care not to damage the grass beneath.


Proper Watering

Adjust Irrigation

  • Adjust your irrigation schedule to reduce moisture levels in the lawn before winter.
  • Water early in the day to allow grass to dry before nighttime, minimizing disease-friendly conditions.

Soil Health

Soil Testing

  • Conduct soil tests to identify nutrient deficiencies and pH imbalances.
  • Amend the soil based on test results to promote optimal grass health.


Maintenance During Dormancy

Limit Traffic

  • Minimize foot traffic and heavy equipment use on the lawn during winter to prevent compaction and injury to dormant grass.

Avoid Fertilizing in Winter

  • Refrain from fertilizing your warm-season lawn during the winter, as it can encourage spring dead spot disease development in cold conditions. If you have cool-season grass such as Kentucky Bluegrass, Perennial Ryegrass, and Turf Type Tall Fescue, we recommend using Stress 12-0-24 - Lebanon Country Club Fertilizer, as it can be applied in cooler conditions as long as your grass is still growing..

Regular Inspections

  • Periodically inspect your lawn throughout winter for any signs of disease. Early detection can lead to more effective treatment.

Apply Fungicides

  • Consider applying fungicides if a disease outbreak occurs or your lawn is particularly susceptible. October and November are ideal for preventative fungicide applications.
  • Follow the label instructions carefully.


Following these prevention strategies can significantly reduce the risk of winter lawn diseases and promote a strong, disease-resistant lawn.


Related reading: Muddy Backyard Solutions: How to Help Drainage for Lawns


Treatment Options to Help Keep Your Lawn Fungus-Free

Treatment Options to Help Keep Your Lawn Fungus-Free

When winter lawn diseases strike, it's essential to take prompt action to minimize damage and restore your lawn to its healthy state. 

Recommended Products

1. Headway G Granular Fungicide

Headway G Granular Fungicide


Headway G granular fungicide combines two active components, azoxystrobin and propiconazole, to deliver exceptional control of fungi that can harm your lawn. This product's unique formulation contains two broad-spectrum fungicides, providing diverse modes of action to target and eradicate winter lawn fungi effectively. 

If you're contending with an active fungi outbreak, we recommend a subsequent application of Headway G fungicide after a 28-day interval. A single 30-pound bag of Headway G can cover an area ranging from 8,500 to 15,000 square feet, contingent on your chosen application rate. This combination fungicide is easy to apply using a broadcast spreader. If you prefer a liquid fungicide, you may want to explore our next recommended product, Pillar SC.

For the best results, apply Headway G in the spring (May or June) and again in the fall (October or November) to proactively control lawn diseases.

We highly recommend this product because its two ingredients combined help prevent and eliminate a wide spectrum of lawn fungi. This means you only have to buy one product, saving time and money. 

Common lawn fungi controlled by Headway G:

  • Brown Patch
  • Dollar Spot
  • Fairy Ring
  • Gray Leaf Spot
  • Large Patch
  • Necrotic Ring Spot
  • Pythium Blight (preventative)
  • Spring Dead Spot
  • And many more (check the label for details).

2. Pillar SC Liquid Fungicide — Brown Patch and Dollar Spot Control

Pillar SC Liquid Fungicide


Pillar SC is a liquid fungicide known for its fast action and impressive control over 26 turf diseases, spanning both cool and warm-season grass types. This versatile solution simplifies disease management by effectively handling common lawn issues such as brown patch, dollar spot, leaf spots, and large patch — all with the ease of a single application rate.

One of its standout features is its expansive coverage, capable of treating areas as extensive as 43,500 square feet, making it a cost-effective choice for larger lawns. Furthermore, its liquid formulation ensures quick disease knockdown, providing a rapid response to disease infestations.

Pillar SC is designed with user-friendliness in mind. It offers a straightforward, one-application-rate-fits-all approach, making it accessible and convenient to use. Combining the strength of two fungicides, Pillar SC delivers long-lasting and comprehensive protection against even the most resilient turf diseases, ensuring your lawn remains disease-free.

Beyond disease control, Pillar SC also contributes to enhancing plant health, fostering the growth of beautiful and robust grass, even in the face of various stressors. Importantly, it is safe for use on all grass types, offering versatility and peace of mind for lawn owners.

3. Stress 12-0-24 - Lebanon Country Club Fertilizer

Stress 12-0-24


To make your grass more resistant to lawn diseases all year round, Country Club Stress 12-0-24 lawn fertilizer is the ultimate choice. This exceptional granular fertilizer, boasting a 12-0-24 stress formulation, is a top-tier option safe for all cool and warm-season grasses. If you aspire to achieve the lushness and resilience seen on golf courses, this could be the fertilizer for you.

The potency of this fertilizer lies in its high potassium content, which empowers your grass to withstand the challenges posed by scorching summer heat and harsh winter conditions. Moreover, it features SOP (Sulfate of Potash) potassium, enhancing plant health while minimizing soil salinity. The inclusion of vital micronutrients like iron, magnesium, and manganese gives your lawn a vibrancy that's unmatched by competitors. 

To enhance the deep green hue of your grass, the formulation incorporates a blend of iron, manganese, and magnesium, addressing any micronutrient deficiencies. In tandem with the high potassium content, this micronutrient combination equips your lawn to resist the stresses of early spring, summer, and winter weather. Completing the nutrient package, Stress 12-0-24 includes Sea Kelp and Humic Acid, optimizing fertilizer uptake and overall plant health.

Ideally, apply this fertilizer every 4 to 6 weeks during your turf's growth phases. For cool-season lawns such as Kentucky Bluegrass, Perennial Ryegrass, and turf-type Tall Fescue, this translates to early spring, the peak of summer, and the winter months.

Warm-season lawns like Bermuda, Zoysia, St Augustine, Centipede, and Bahia benefit greatly from early spring through fall fertilizer applications. This well-rounded formulation provides sustained nourishment for your lawn and soil throughout the entire growing season.


Related reading: The Most Effective Fungicides to Use on Your Lawn


Have a Disease-Free Lawn This Winter

Maintaining a disease-resistant lawn ensures a beautiful and vibrant outdoor space and also reduces the need for costly disease treatments and repairs. Remember that proper lawn care practices, selecting the right grass varieties, and using the best fungicides for lawns are pivotal in promoting a resilient lawn. Whether you're dealing with common winter lawn diseases like Snow Mold and Brown Patch or seeking to prevent future outbreaks, the key is proactive care.

Golf Course Lawn can help you prevent and eliminate invasive lawn fungi. Browse our range of highly effective insecticides and fungicides to get a healthy, vibrant lawn.